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Networked Audio Systems

It is quite common for larger customers to have mutliple premises each with it's own PA system and often there is the need to make announcments over all sites. Historically this has been acheived using telephony standards which resulted in poor audio quality due to the restricted bandwidth of the telephone network, and often having to pay an annual rent for the use of private wire connections.

Now with the advent of TCP/IP we can transmit multiple, simultaneous channels of very high quality audio (24-bit) with full system control over a customers existing data network.

The heart of our Network Audio Systems is QSC Audio's BASIS and RAVE range of CobraNet enabled digital signal processors. CobraNet is an 100Mb Ethernet protocol specifically developed for the transmission of audio. The CobraNet enabled RAVE and BASIS units have two RJ-45 network connection ports on the rear panel. One port is labeled "QSControl" and supports standard 10Mb Ethernet. The other port is labeled "CobraNet" and supports 100Mb Ethernet, also known as "Fast Ethernet".

These RAVE and BASIS units support two distinct kinds of network activity; the first is audio transport via CobraNet, and the second is QSControl. net. The user can choose to install one network for CobraNet traffic and a second separate network for QSControl.net traffic. We call this the "Two Wire Interface". Alternately, it is possible to run both QSControl.net data and audio traffic via the CobraNet port. We call this the "Single Wire Interface". Under the most demanding real-time control conditions and when using the lowest latency CobraNet settings, users may experience better QSControl.net performance using separate networks, especially when displaying a great many real-time meters. For most applications, separate networks won't provide any discernible benefits and will cost more. We therefore recommend using the Single Wire Interface when running CobraNet.

Why CobraNet? Ordinary Ethernet traffic has no guaranteed time of delivery. Packets of information may arrive at their destination out of order and some may be delayed more than others. This is fine for E-mail and even for downloading MP3 files over the Internet. Everything ends up properly reassembled at the destination, but how long this takes will vary according to network loading, span, etc. In contrast, CobraNet is "real time". It delivers audio with a minimal, consistent transmission delay. CobraNet is designed to use as much of conventional networking technology as possible while providing both guaranteed time of delivery and isochronicity - maintaining a phase-locked sample-accurate clock across the entire network.

For less demanding applications we can also offer TOA's NX100 Network adaptor, and we are currently investigating the use of Valcom's VoIP equipment.

Please contact us if you require further information.

CobraNet Topologies


QSControl cross over


CobraNet cross over


Single wire


2-wire (shared network hardware)


2-wire (separate network hardware)

Brochures

QSC CobraNet

TOA NX100

Product Ranges & Services

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We have just completed an installation using two of QSC Audio's RAVE 522ua units to link Heysham 1's Voice Alarm system to the sites simulator suite located in Heysham 2.

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Design & Maintenance